<?php
/** 
 * Copyright (c) 2002-2006 Martin Jansen
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the 
 * "Software"), to deal in the Software without restriction, including 
 * without limitation the rights to use, copy, modify, merge, publish, 
 * distribute, sublicense, and/or sell copies of the Software, and to 
 * permit persons to whom the Software is furnished to do so, subject to 
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included 
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 * DEALINGS IN THE SOFTWARE.
 *
 */

/**
 * Class to validate the syntax of IPv4 adresses
 *
 * Usage:
 *   <?php
 *   require_once 'Net/CheckIP.php';
 *
 *   $ip = 'your_ip_goes_here';
 *   if (PEAR2_Net_CheckIP::check_ip($ip)) {
 *       // Syntax of the IP is ok
 *   }
 *   ?>
 *
 * @author  Martin Jansen <mj@php.net>
 * @author  Guido Haeger <gh-lists@ecora.de>
 * @author  Till Klampaeckel <till@php.net>
 * @todo    Add an IPv6 check.
 * @package Net_CheckIP2
 * @version 0.0.1
 */
class PEAR2_Net_CheckIP
{
    /**
     * Force usage of check_ip
     *
     * @access private
     * @see    PEAR2_Net_CheckIP::check_ip()
     */
    private function __construct()
    {}

    /**
     * Validate the syntax of the given IP adress
     *
     * This function splits the IP address in 4 pieces
     * (separated by ".") and checks for each piece
     * if it's an integer value between 0 and 255.
     * If all 4 parameters pass this test, the function
     * returns true.
     *
     * @access static
     * @param  string $ip IP adress
     * @return bool   true if syntax is valid, otherwise false
     */
    static function check_ip($ip = '')
    {
        $oct = explode('.', $ip);
        if (count($oct) != 4) {
            return false;
        }
        for ($i = 0; $i < 4; $i++) {
            if (!preg_match("/^[0-9]+$/", $oct[$i])) {
                return false;
            }
            if ($oct[$i] < 0 || $oct[$i] > 255) {
                return false;
            }
        }
        return true;
    }
}